This application is a continuation of International Application No. PCT/JP2005/016147, filed Sep. 2, 2005.
1. Field of the Invention
The present invention relates to a network interface control program and a network interface controller for controlling a plurality of network interfaces connected to a network repeater, and, more particularly to a network interface control program and a network interface controller for automatically executing band expansion/reduction according to communication situation to provide an appropriate communication band.
2. Description of the Related Art
Conventionally, band expansion/reduction processing in communication via the network interface (network IF) has been performed manually. For example, in a server, when a communication failure such as delay in a communication response time occurs due to an increase of communication traffic, as a method for handling the problem, a cause thereof is specified by human determination based on statistics of CPU load and data transmission amount, and an operation for adding the network IF is performed manually to expand the band in communications. With this method, however, manual traffic management and an expansion operation are required, thereby causing a large cost increase.
For the expansion of the communication band, human labor can be reduced by securing beforehand a broadband transmission line capable of preventing a communication failure due to an increase of the traffic beforehand. Particularly, when a cost aspect is taken into consideration, a method of forming a plurality of transmission lines between the network IF and a LAN switch is effective as a method of band expansion. As one example thereof, there is link aggregation prescribed in IEEE 802.3ad (for example, see IEEE P802.3ad Link Aggregation Task Force [Searched on Aug. 23, 2005], Internet <URL:http://grouper.ieee.org/groups/802/3/ad/index.html>). In the link aggregation, a plurality of transmission lines is virtually regarded as one transmission line, so that the communication band can be expanded and redundancy can be provided to the transmission line.
In the link aggregation prescribed in IEEE 802.3ad, there is provided a function for recovering a communication state, when a communication failure occurs in a part of a plurality of grouped communication lines, and the LAN switch detects the failure, by excluding the transmission line having the detected failure from a grouping target. However, this function only corresponds to a communication failure detectable by the LAN switch, such as physical disconnection, and flexible band change cannot be executed corresponding to a temporary communication failure such as a traffic increase.
In view of the above problems, it is an object of the present invention to provide a network interface program and a network interface controller for automatically executing band expansion/reduction according to band usage, to provide an appropriate communication band.